催化学报 ›› 2018, Vol. 39 ›› Issue (4): 760-770.DOI: 10.1016/S1872-2067(17)62978-4

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具有超快电子传输能力的金/薄层氮化碳等离子光催化剂用于光催化产氢

莫曌a, 许晖a, 陈志刚a, 佘小杰a, 宋艳华b, 严鹏程a, 徐远国a, 雷玉成a, 袁寿其a, 李华明a   

  1. a 江苏大学材料科学与工程学院, 能源研究院, 江苏镇江 212003;
    b 江苏科技大学环境与化工学院, 江苏镇江 212003
  • 收稿日期:2017-11-30 修回日期:2017-12-31 出版日期:2018-04-18 发布日期:2018-04-08
  • 通讯作者: 许晖, 雷玉成, 李华明
  • 基金资助:

    国家自然科学基金(21476097,21776118);江苏省六大人才高峰项目(2014-JNHB-014);江苏省自然科学基金(BK20161363);江苏省研究生培养创新工程(KYCX17-1769);江苏高校优势学科建设资助项目.

Gold/monolayer graphitic carbon nitride plasmonic photocatalyst for ultrafast electron transfer in solar-to-hydrogen energy conversion

Zhao Moa, Hui Xua, Zhigang Chena, Xiaojie Shea, Yanhua Songb, Pengcheng Yana, Yuanguo Xua, Yucheng Leia, Shouqi Yuana, Huaming Lia   

  1. a School of Materials Science & Engineering, Institute for Energy Research, Jiangsu University, Zhenjiang 212003, Jiangsu, China;
    b School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu, China
  • Received:2017-11-30 Revised:2017-12-31 Online:2018-04-18 Published:2018-04-08
  • Contact: 10.1016/S1872-2067(17)62978-4
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21476097, 21776118), the Six Talent Peaks Project in Jiangsu Province (2014-JNHB-014), the Natural Science Foundation of Jiangsu Province (BK20161363), the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX17-1769), and the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.

摘要:

光催化产氢可以直接将太阳能转化为化学能,是非常有前景的产氢技术之一.然而,光催化产氢的瓶颈在于如何提高光催化产氢效率和光催化剂的稳定性,以及降低产氢成本.因此,开发廉价、易于制备的产氢光催化剂引起人们广泛关注.作为一种非金属半导体光催化剂,石墨相氮化碳(g-C3N4)具有良好的物理化学性质,如良好的化学和热稳定性、极佳的光电性能、强的抗氧化能力等.更为重要的是,g-C3N4具有合适的能带结构,能够利用可见光.因此,g-C3N4已广泛应用于光催化降解、空气净化、光解水和光催化CO2还原等领域.然而,体相g-C3N4仍然暴露出一些缺点,例如比表面积小、光生电子-空穴对的复合率高和反应动力学差等.将体相g-C3N4剥离成g-C3N4纳米薄片是提高光催化效率的有效方法.薄层g-C3N4纳米片具有较高的比表面积,比体相的g-C3N4有更好的光生电子-空穴对分离效率.
为了进一步提高g-C3N4的光催化性能,本文通过在薄层g-C3N4表面均匀分散Au纳米颗粒来控制电荷载流子的流动.并通过光催化产氢和污染物降解来评估金/薄层氮化碳(Au/monolayer g-C3N4)复合材料的光催化性能.所有的Au/薄层g-C3N4复合材料均显示出优于体相g-C3N4的光催化性能,其中1% Au/薄层g-C3N4复合光催化剂具有最高的产氢速率(565μmol g-1 h-1),且具有最佳的污染物降解能力.这主要归结于热电子的注入,而不是肖特基结.Au纳米颗粒的成功引入带来了表面等离子共振(SPR)效应,SPR效应不仅能够提高光吸收效率,而且能够带来高效的热电子转移途径.热电子是从Au纳米颗粒表面注入到薄层g-C3N4纳米片的导带上.因此,Au/薄层g-C3N4复合光催化剂具有更高的光生电子-空穴对迁移和分离效率,以及更低的光生电子-空穴对复合几率.
采用紫外可见光谱(UV-Vis)、光致发光光谱(PL)、光电流和阻抗等表征手段研究了Au/薄层g-C3N4复合光催化剂性能提升的原因.结果表明,相比于薄层g-C3N4纳米片,Au/薄层g-C3N4复合光催化剂具有更好的光电性能,因而光催化活性更高.此外,与薄层g-C3N4纳米片的光电流强度相比,Au/薄层g-C3N4复合光催化剂的光电流强度没有发生改变,这表明薄层g-C3N4纳米片导带上的光生电子不可能转移到Au纳米颗粒的表面.也就是说,肖特基结并没有参与到电子转移过程中,因此推测出整个光催化反应是热电子注入在起作用.

关键词: 单层氮化碳, 金等离子纳米颗粒, 光催化产氢, 热电子, 金/单层氮化碳

Abstract:

Gold (Au) plasmonic nanoparticles were grown evenly on monolayer graphitic carbon nitride (g-C3N4) nanosheets via a facile oil-bath method. The photocatalytic activity of the Au/monolayer g-C3N4 composites under visible light was evaluated by photocatalytic hydrogen evolution and environmental treatment. All of the Au/monolayer g-C3N4 composites showed better photocatalytic performance than that of monolayer g-C3N4 and the 1% Au/monolayer g-C3N4 composite displayed the highest photocatalytic hydrogen evolution rate of the samples. The remarkable photocatalytic activity was attributed largely to the successful introduction of Au plasmonic nanoparticles, which led to the surface plasmon resonance (SPR) effect. The SPR effect enhanced the efficiency of light harvesting and induced an efficient hot electron transfer process. The hot electrons were injected from the Au plasmonic nanoparticles into the conduction band of monolayer g-C3N4. Thus, the Au/monolayer g-C3N4 composites possessed higher migration and separation efficiencies and lower recombination probability of photogenerated electron-hole pairs than those of monolayer g-C3N4. A photocatalytic mechanism for the composites was also proposed.

Key words: Monolayer g-C3N4, Au plasmonic nanoparticle, Photocatalytic hydrogen evolution, Hot electron, Au/monolayer g-C3N4